DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application is being examined under the pre-AIA first to invent provisions.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 11/11/2025 has been entered.
Claim Status
No new claim amendments have been made. Claims 2-4, 7, 10, 17-20, 23-30, and 39-44 are cancelled. Claims 1, 5-6, 8-9, 11-16, 21-22, and 31-38 are pending in the instant application.
Claims 8-9 and 12 stand as withdrawn from further consideration pursuant to 37 CFR 1.142(b), as being drawn to a nonelected invention in the Response filed 02/16/2024, there being no allowable generic or linking claim.
Claims 1, 5-6, 11, 13-16, 21-22, and 31-38 are under examination in the instant office action.
Claim Rejections - 35 USC § 112 - New
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1, 5-6, 11, 13-16, 21-22, and 31-38 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 recites the limitation “the chromatography effluent from steps a) and b)” in lines 10-11. There is insufficient antecedent basis for this limitation in the claim. It is noted that step a) is drawn to a loading step, but it is not explicitly indicated that any effluent is collected and it is known that loading steps may be performed without generating/collecting effluent. Further with regard to claim 1, the recitation of “the dynamic binding capacity” in lines 4-5 and “the partition coefficient” in line 6 further renders the claim indefinite. It is noted that the binding capacity is variable in chromatography across chromatography materials, and similarly the partition coefficient is variable depending on the identity of the target molecules and/or proteins (i.e., antibodies) that are binding the chromatography material. As currently presented, claim 1 does not teach a specific antibody nor what chromatography conditions are being used, and as such the metes and bounds of the claim are unclear.
The term “about” in claims 13-14, 21-22, 32-33, and 35-36 is a relative term which renders the claim indefinite. The term “about” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. It is unclear as to what degree of deviation with regard to the recited limitations (i.e., loading density, conductivity, or pH) would be considered acceptable.
Claims 5-6, 11, 15-16, 31, 34, and 37-38 are included in this rejection as they depend from/incorporate 1.
Claim Rejections - 35 USC § 103 - Updated
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
The factual inquiries for establishing a background for determining obviousness under pre-AIA 35 U.S.C. 103(a) are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims under pre-AIA 35 U.S.C. 103(a), the examiner presumes that the subject matter of the various claims was commonly owned at the time any inventions covered therein were made absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and invention dates of each claim that was not commonly owned at the time a later invention was made in order for the examiner to consider the applicability of pre-AIA 35 U.S.C. 103(c) and potential pre-AIA 35 U.S.C. 102(e), (f) or (g) prior art under pre-AIA 35 U.S.C. 103(a).
Claims 1, 5-6, 11, 13-16, 21-22, and 31-38 stand as rejected under pre-AIA 35 U.S.C. 103(a) as being unpatentable over US 2013/0331554 A1 (previously cited on PTO-892; herein after referred to as "Ladiwala") in view of non-patent literature published by Brown et. al. (Biotechnol. Appl. Biochem., 2010, 56, 59-70; previously cited on PTO-892; herein after referred to as "Brown") and non-patent literature published by Voitl et. al. (Journal of Chromatography A, 2010, 1217, 5753-5760; previously cited on PTO-892; herein after referred to as "Voitl").
It is noted that the claim rejections below have been updated for clarity of the record regarding the motivation to combine the teachings of the prior art references to arrive at the instantly claimed invention in view of Applicant’s arguments, which are further discussed below.
With regard to claim 1, Ladiwala teaches a method for enhancing or increasing the concentration of biological product in a final mixture, wherein said biological product has one or more selected characteristics, wherein said method comprises: (a) allowing an initial mixture of biological products with and without said selected characteristics to contact a chromatography medium wherein the quantity of biological products in said initial mixture exceeds the binding capacity or the dynamic binding capacity of said chromatography medium; (b) allowing biological product not having said one or more selected characteristics to be separated by said chromatography medium; and (c) recovering a final mixture of biological products from said chromatography medium wherein said final mixture comprises an enhanced or increased concentration of biological product with one or more selected characteristics, compared to the concentration of biological product in said initial mixture (Abstract; emphasis added). The method of the invention utilizes an "overload bind and elute" mode of operation wherein a biological product is allowed to contact a chromatography medium (or other matrix) at a concentration or in an amount which exceeds the static or the dynamic binding capacity of the chromatography medium (or other matrix): during the overload and bind step, biological product having a selected characteristic (such as a high overall net-negative charge or a high sialic acid content) preferentially binds to the chromatography medium (or other matrix) while biological product (as well as other impurities) not having the selected characteristic, or having less of the selected characteristic (such as biological product having a lower overall net negative charge or a lower sialic acid content) is excluded or separated from the medium (or matrix); subsequent to the overload and bind step, the bound target product is eluted (or otherwise dissociated or separated) from the chromatography medium (or other matrix) and recovered such that the biological product mixture obtained has been enriched with a higher concentration of product having the selected (target) characteristic compared to the product mixture prior to application of the overload bind and elute purification step (Paragraph 0037; emphasis added). Methods of the invention can be adapted and applied to the separation/purification of biological products based on any number of physical, biological, and/or chemical characteristics; for example, product isoforms may be selectively separated on the basis of charge and/or hydrophobicity by using appropriate adsorbents (such as, for example, strong or weak anion or cation exchange resins for charge-based separations and hydrophobic adsorbents for separations based on hydrophobicity) and methods of the invention may be applied using mixed-mode chromatography (mixed-mode media) for separations based on two orthogonal product attributes (e.g., charge and hydrophobicity) (Paragraph 0038; emphasis added). Embodiments of the invention are useful for obtaining highly homogeneous mixtures of a wide variety of biological products; some examples of such biological products include, without limitation, proteins and protein fragments (i.e., full-length and partial length polypeptides/peptides), antibodies (immunoglobulins), heterologous fusion proteins, etc. (Paragraph 0041). Embodiments of the invention include use of any known, or subsequently disclosed or developed, chromatography media or matrix wherein examples, without limitation, of such media comprise: ion exchange media; anion exchange media; cation exchange media; hydroxyapatite media; hydrophobic interaction chromatography media; antibody-affinity media (e.g., Protein-A or variants thereof); immunoglobulin Fc-region affinity media (e.g., Fc-receptor affinity media); and, ligand-affinity media; receptor-affinity media; and mixed-mode media (Paragraph 0047; emphasis added). Embodiments of the invention include methods wherein the binding capacity or dynamic binding capacity of a chromatography medium is exceeded by: 10% or more; 20% or more; 30% or more; 40% or more; 50% or more; 100% or more; 200% or more; 500% or more; and 1000% or more (Paragraph 0048). Section 3.3 under “METHODS” details preliminary method development: (i) the column was pre-equilibrated with 3CVs of 50 mM Tris/ 3M NaCl, pH 8.0; (ii) the column was equilibrated with 5 CVs of 50 mM Acetate, pH 5.5; (iii) the column was loaded to the target loading condition with the load pool at the appropriate pH; (iv) the column was washed with 3 CVs of the equilibration solution; (v) the column was eluted with 8 CVs of 50 mM Acetate + 300 mM NaCl, pH 5.5 and eluate pool collection was started at the start of the elution step and concluded when OD280 of ≤ 0.l AU was reached; (vi) the column was stripped with 3 CVs of 50 mM Tris + 3M NaCl, pH 8.0; (vii) the column was cleaned with 3 CVs of 0.5 M NaOH; (viii) the column was regenerated with 3 CVs of 50 mM Acetate + 1 M NaCl, pH 2.5; and (ix) the column was stored with 3CVs of 1% Benzyl alcohol + 0.5 M Acetic Acid + 16 mM NaOH, pH 3.2 (Paragraphs 0120-0130). Thus, Ladiwala teaches a method for product (e.g., antibody) enrichment comprising an “overload bind and elute” mode of operation wherein a composition/mixture in a loading buffer is loaded onto a column (e.g., mixed mode, anion exchange, hydrophobic, or affinity) in excess of the dynamic binding capacity for the desired product and the desired product is subsequently eluted with an elution buffer while contaminants/undesired products remain on the column. It is further noted that Ladiwala also teaches that the amount of product recovered in the final mixture can be about 80% (Paragraph 0050) and the biological products targeted by the method can be increased compared to the initial mixture by at least 90% (Paragraph 0051). It is noted this refers only to the eluate pool, as Ladiwala does not teach pooling load flow-through containing antibody and eluate antibodies. Additionally, it is noted that Ladiwala does not teach a partition coefficient of greater than 30, an elution buffer having a conductivity less than that of the loading buffer, nor pooling fractions comprising an antibody from the load and elution steps. These deficiencies are remedied by Brown and Voitl.
Brown teaches overloading of ion-exchange membrane adsorbers, a form of frontal chromatography, as the final purification step in the production of mAbs (monoclonal antibodies) produced from CHO (Chinese-hamster ovary) cells wherein the preferential binding of impurities over antibody product was exploited such that impurities were retained on the membrane adsorbers while there was breakthrough of purified antibodies (Abstract; emphasis added). While the studies disclosed in Brown are exclusive to membrane adsorbers, Brown notes that packed bed resins are favored over membranes in cases wherein it is desired that the antibody bind tighter than impurities due to superior binding capacity and lower costs (Page 62, Column 2, Paragraph 2; emphasis added). Thus, Brown teaches that while methods wherein contaminants are retained have been demonstrated to be successful, methods of overload chromatography with packed bed resins are also contemplated. More specifically, Brown teaches loading a cation-exchange membrane Mustang at pH 5.5 and 6.0 mS/cm with 16 kg mAb per L membrane and loading a small scaler Mustang S membrane with 1, 5, 10, and 15 kg mAb per L membrane then chasing with a buffer after which the membranes were eluted in a linear gradient with sodium chloride wherein samples were collected during overloading and fractions were collected during the gradient elution (Page 67, Column 2). Brown elucidated the binding properties of the mAbs and contaminant proteins as demonstrated in Figure 8, which reveals preferential elution of mAb at low salt concentration (i.e., between fractions 2 and 4) wherein milligrams of antibody could be eluted with only nanograms of CHOP co-eluting; Brown states that (i) because the gradient moves from low to high salt concentration, the position in the gradient elution provides some insight into the strength of binding wherein the results suggest that gentamicin binds stronger than CHOP, which binds stronger than monomers; and (ii) as mAb loading increased from 1 to 15 kg mAb/L membrane, the levels of monomer decreased, while CHOP and gentamicin increased possibly because CHOP and gentamicin displace monomers on the membrane surface (e.g., during overloading wherein more mAb would be expected to be in the flowthrough) (Page 68, Column 2, Paragraph 1). It would be within the purview of one having ordinary skill in the art that in addition to antibody obtained during the overloading step, sufficiently purified antibody may also be obtained during the elution step and it would be desirable to pool as much sufficiently pure product as possible. It is also specifically noted that the Mustang S membrane has a binding capacity with an upper limit of approximately 30 g mAb per L membrane (Page 63, Column 1, Paragraph 2).
Voitl systematically explores the possibilities of Capto adhere, a mixed mode resin, as a stationary phase for the polishing of antibodies wherein through the analysis of the retention time of various model proteins, it was possible to predict the separation of artificial mixtures of proteins on Capto adhere and examples for Capto adhere usage in the polishing step of a monoclonal antibody (mAb) purification process is discussed (Page 5754, Column 1, Paragraph 1). One variable analyzed in the studies included the Henry coefficient, wherein a low Henry coefficient corresponds to conditions where binding is negligible while a high Henry coefficient corresponds to conditions of significant adsorption (Page 5754-5755). It is specifically noted that one of ordinary skill in the art would recognize the Henry coefficient as a partition coefficient; the ratio of the amount of product adsorbed (i.e., solid phase) versus concentration in bulk solution (i.e., mobile phase). The study evaluated the effect of both pH and conductivity (i.e., salt concentration) on the Henry coefficient of various proteins with the Capto adhere stationary phase (Page 5756-5758, Henry coefficients of proteins on Capto adhere; Figures 3-4). It is specifically noted that Figures 3-4 demonstrate Henry coefficients from 10-1 up to 102 are achievable by adjusting pH and/or salt concentration for Capto adhere mixed mode resin. More specifically, Voitl teaches that increasing pH increased the Henry coefficient, and thus increased binding, of all proteins evaluated when NaCl was present (Figure 3) while increasing salt concentration also generally increased the Henry coefficient for the proteins at various pH values (Figure 4). The relationship between Henry coefficient and pH/salt concentration for Capto adhere is also shown in Figure 5. Thus, overall Voitl demonstrates that increased pH under constant salt conditions increases binding capacity, while increased salt concentration under constant pH also generally increases binding capacity. Therefore, when trying to bind and elute an antibody from mixed-mode resin, reduced pH values under similar salt conditions or reduced salt concentration (i.e., reduced conductivity) under similar pH conditions compared to the loading buffer would be desired; a high Henry coefficient/partition coefficient to load maximizes the amount of antibody bound, while lowering the Henry coefficient of the antibody while eluting is necessary to purify the antibody by eluting the antibody from the column.
It is also noted, as evidenced by the references, that the column utilized, binding capacity, partition coefficient, pH, and conductivity were recognized as antibody purification variables which achieve a recognized result and as set forth in MPEP 2144.05: “A particular parameter must first be recognized as a result-effective variable, i.e., a variable which achieves a recognized result, before the determination of the optimum or workable ranges of said variable might be characterized as routine experimentation. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). It is a common objective in the art to optimize result effective variables, so as achieve optimal effect and maximal benefit. See In re Boesch, 617 F.2d 272, 276, 205 USPQ 215, 219 (CCPA 1980) (“[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art.” (citations omitted)). Therefore, any optimization of column utilized, binding capacity, partition coefficient, pH, and conductivity would be seen as routine optimization.
Ladiwala, Brown, and Voitl are considered to be analogous to the present invention as they are in the same field of chromatography for methods of product enrichment/purification. Thus, it would have been obvious to one of ordinary skill in the art to use the “overload bind and elute” method of Ladiwala wherein an antibody is loaded onto a chromatography column (selected based on the property to be exploited for purification) in excess of the dynamic binding capacity for said antibody, wherein the method could be modified, as suggested by Brown, such that the impurities of the initial loading mixture preferentially bind the chromatography matrix (i.e., antibody is part of the eluate of the overload step) wherein an elution step may then be performed such that an elution buffer is selected wherein any antibody that bound the chromatography matrix is selectively eluted while undesired products/contaminants remain bound to the column. Said elution buffer would differ from the load buffer, as suggested by Ladiwala, Brown, and Voitl, wherein the partition coefficient is maximized during loading (e.g., partition coefficient > 30) and conductivity of the elution buffer is lower than that of the loading buffer, as suggested by Voitl. The method could be further modified such that the antibody-containing eluate from the overload step and eluate fractions containing antibody from the elution step can be identified and collected wherein said antibody-containing eluate from the overload and elution steps can subsequently be pooled, as suggested by Brown, in order to optimize the amount of purified antibody collected. Combining prior art elements according to known methods would be expected to yield predictable results with a reasonable expectation of success. Both Ladiwala and Brown disclose the use of overload and elute methods for the purification/enrichment of biological products (e.g., antibodies) wherein undesired products/contaminants can be selectively removed utilizing column chromatography, and thus the combination of teachings would be expected to yield a method of purifying an antibody with a reasonable expectation of success as established by both Ladiwala and Brown; additionally, it would have been within the purview of one having ordinary skill in the art to optimize such a method to selectively purify an antibody from a mixture comprising contaminants by optimizing the column, binding capacity, partition coefficient, and buffers, as supported by all of the cited references, with the motivation of retaining/purifying as much antibody as possible while removing as many contaminants as possible.
With regard to claims 5-6, Ladiwala suggests the enrichment of products such as antibodies while Brown and Voitl specifically disclose the purification of monoclonal antibodies, wherein Voitl specifically discloses both chimeric and humanized antibodies (Erbitux and Avastin, respectively). Therefore, the invention as a whole was prima facie obvious to one of ordinary skill in the art at the effective filing date of the invention as evidenced by the references.
With regard to claim 11, Brown teaches experiments that explore how clearance of host cell proteins (e.g., impurity/contaminant CHOP) was affected by pH, conductivity, flow rate, membrane properties, and scale (Abstract). Therefore, the invention as a whole was prima facie obvious to one of ordinary skill in the art at the effective filing date of the invention as evidenced by the references.
With regard to claims 13-14, Brown teaches loading with 1, 5, 10, and 15 kg mAb per L membrane (Page 67, Column 2), which is in excess of the binding capacity of the membrane disclosed as approximately 30 g mAb per L membrane (Page 63, Column 1, Paragraph 2). Therefore, the invention as a whole was prima facie obvious to one of ordinary skill in the art at the effective filing date of the invention as evidenced by the references.
With regard to claim 15, while none of the references explicitly disclose loading the chromatography material at about the dynamic binding capacities of the chromatography materials for the one or more contaminants, as detailed above the binding capacity, partition coefficient, pH, and conductivity were recognized as antibody purification variables. It is specifically noted that Ladiwala, Brown, and Voitl explicitly teach methods for enrichment/purification wherein specific, desired products (e.g., antibodies) are overloaded and specifically eluted in order to separate them from impurities. Therefore, the invention as a whole was prima facie obvious to one of ordinary skill in the art at the effective filing date of the invention as evidenced by the references.
With regard to claim 16, Brown teaches loading with 1, 5, 10, and 15 kg mAb per L membrane (Page 67, Column 2). The binding capacity of the membrane disclosed as approximately 30 g mAb per L membrane (Page 63, Column 1, Paragraph 2). Loading at 600 g mAb per L membrane would be loading at 20 times the binding capacity for the antibody, which Brown exceeds as detailed above. Therefore, the invention as a whole was prima facie obvious to one of ordinary skill in the art at the effective filing date of the invention as evidenced by the references.
With regard to claim 21, Brown teaches loading a cation-exchange membrane Mustang at pH 5.5 and 6.0 mS/cm while Voitl teaches loading at a pH 7.5–8.5 and conductivity of at least 13 mS/cm. As detailed above, the binding capacity, partition coefficient, pH, and conductivity were recognized as antibody purification variables. Thus, one of ordinary skill in the art could determine optimum operating conditions with regard to loading buffer conductivity with the motivation of developing an optimized and efficient purification method that retains high product purity/yield.
With regard to claim 22, Voitl teaches that high salt concentrations cause all proteins to elute later (Page 5758, Column 1, Paragraph 2) and demonstrated that increasing salt concentration generally increased the Henry coefficient, increased adsorption, for the proteins to the mixed-mode stationary phase at various pH values (Figure 4). As detailed above, the binding capacity, partition coefficient, pH, and conductivity were recognized as antibody purification variables. Thus, one of ordinary skill in the art could determine optimum operating conditions with regard to elution buffer conductivity, and as suggested by the teachings of Voitl the concentration of salt (i.e., conductivity) would be lower than that of the loading buffer to get the antibody to elute, with the motivation of developing an optimized and efficient purification method that retains high product purity/yield.
With regard to claims 31-36, Voitl teaches that the Capto adhere stationary phase shows a broad range of Henry coefficients: high Henry coefficients are reached at high salt concentrations, but also without salt and elevated pH, indicating that binding conditions might be selected from a wider range of conditions compared to conventional stationary phases, leading to a greater flexibility to optimize the separation and purification of proteins (Page 5758, Column 1, Paragraph 2). Brown also teaches various loading/elution buffer pH values for the cationic/anionic membranes (load between pH 5.5-8 and elute between 5.5-8; noted that conductivity/salt concentrations also varied) (Page 62, Column 1, Experimental; Table 1). As detailed above, the binding capacity, partition coefficient, pH, and conductivity were recognized as antibody purification variables. Thus, one of ordinary skill in the art could determine optimum operating conditions with regard to load/elution buffer composition/pH, and as suggested by the teachings of Voitl. Therefore, while Voitl teaches loading/feed pH values between 7-8 and elution pH values of 4, one of ordinary skill in the art could determine optimum operating conditions with regard to load/elution buffer pH, as suggested by Voitl and Brown, wherein the pH values for either buffer could range from 4-9 depending on the antibody of interest and/or other purification conditions; i.e., the pH of the was buffer may be higher or lower than the elution buffer depending on the exact set of operating conditions. The motivation for such optimization would be to develop an optimized and efficient purification method that retains high product purity/yield.
With regard to claims 37-38, Brown teaches a step wherein what is loaded onto the chromatography material is Protein A pool (i.e., eluant from an initial Protein A affinity purification) (Page 60, Materials and Methods). Therefore, the invention as a whole was prima facie obvious to one of ordinary skill in the art at the effective filing date of the invention as evidenced by the references.
Response to Arguments
Applicant's arguments filed 11/11/2025 (herein after referred to as “Remarks”) have been fully considered but they are not persuasive. Applicant argues the following on Pages 6-16 of Remarks:
There is no motivation to combine the cited prior art references with a reasonable expectation of success in view of: (1) the absence of the recited “pooling” and “elution” steps from the method of Ladiwala allow the method to achieve its purpose of enhancing or increasing the concentration of biological product in a final mixture. The intended purpose of Ladiwala is necessarily achieved by the method of Ladiwala operating such that "[d]uring the overload and bind step, biological product having a selected characteristic (such as a high overall net-negative charge or a high sialic acid content) preferentially binds to the chromatography medium (or other matrix) while the biological product (as well as other impurities) not having the selected characteristic ... is excluded or separated from the medium (or matrix)."
There is no motivation to combine the teachings of Ladiwala and Brown; modifying the method of Ladiwala to, instead, pool the eluted fraction with the flowthrough fraction obtained during the loading step of Ladiwala would clearly destroy this intended purpose by combining the desired antibody product with undesired antibody products and other impurities, which would necessarily decrease the concentration of the desired biological product in the final mixture. There would be no reason or motivation for a POSIT A to modify the method of Ladiwala so that the flow through that contains undesired product and impurities would be pooled with the eluted fraction containing the desired product.
A POSITA would clearly find no reason or motivation to modify the method of Ladiwala as alleged by the Office, particularly since it would be counterintuitive and would destroy its intended purpose of enriching or increasing the concentration of its desired product.
The method of Ladiwala "was developed wherein the higher sialylated glycoforms having higher net negative charge and binding affinity to TMAE HiCap competed effectively for binding sites with the lower affinity lesser sialylated and non-sialylated glycoforms, thus displacing these lower affinity species"; the Office has not explained whether and how such a method could be altered such that the lesser sialylated glycoforms and other impurities would preferentially bind to the chromatography column and further modified such that fractions collected during the overload step and elution step could be pooled to still achieve the intended purpose of enriching or increasing the concentration of the desired highly sialylated glycoform in a final mixture, and with a reasonable expectation of success.
There would lack predictability in whether modifying the method of Ladiwala based on Brown as alleged by the Office would be effective in purifying an antibody from a composition comprising the antibody and one or more contaminants, since Brown operates opposite from Ladiwala in terms of whether the desired product or undesired product/impurities preferentially bind the column, thereby introducing unpredictability in how, if at all, Ladiwala could be modified to achieve purification of an antibody from contaminants without destroying its intended purpose of "enhancing or increasing the concentration of biological product in a final mixture."
The proposed modification of collecting and pooling the "flow though" from the overload step of Ladiwala would have "amounted to extra work and greater expense for no apparent reason"; Ladiwala teaches that the flow through includes the undesirable lesser sialylated glycoforms and other impurities, thereby providing no apparent reason why a POSITA would want to collect such flow through and pool it with the desired highly sialylated glycoform that is later eluted at an enriched or enhanced concentration, which is the whole point of Ladiwala's method.
Neither Ladiwala nor Brown involve, inter alia, the recited pooling step, as they each relate to a different approach for purification without any teaching or contemplation of any modification such that the pending claims, including the recited pooling step, could be achieved with a reasonable expectation of success, and without the use of impermissible hindsight bias using Applicant's disclosure as a roadmap; Ladiwala explicitly teaches that its flow though preferentially contains the undesirable lesser sialylated glycoform and other impurities. Thus, the data in Examples 5-10 of the Examples of the present application showing very low amounts of impurities in the pooled fractions would have been unexpected to a POSITA wherein the claimed OEC mode achieves unexpected results by, inter alia, demonstrating that the recited conditions can be used such that chromatography effluent from the recited overload step of a) can be pooled with the recited eluting step of b) and result in high yield, high purity, and high volume processing which is highly advantageous, especially for commercial manufacturing.
With regard to arguments (i)-(iii) regarding the motivation to combine, it is noted that in response to Applicant's piecemeal analysis of the references, it has been held that one cannot show non-obviousness by attacking references individually where, as here, the rejections are based on combinations of references. In re Keller, 208 USPQ 871 (CCPA 1981). Ladiwala is relied upon for its teaching of a method for enhancing or increasing the concentration of biological product in a final mixture wherein said biological product has one or more selected characteristics and wherein said method comprises: (a) allowing an initial mixture of biological products with and without said selected characteristics to contact a chromatography medium wherein the quantity of biological products in said initial mixture exceeds the binding capacity or the dynamic binding capacity of said chromatography medium; (b) allowing biological product not having said one or more selected characteristics to be separated by said chromatography medium; and (c) recovering a final mixture of biological products from said chromatography medium wherein said final mixture comprises an enhanced or increased concentration of biological product with one or more selected characteristics, compared to the concentration of biological product in said initial mixture. The method utilizes an “overload bind and elute” mode of operation. Ladiwala also suggested that methods of the invention can be adapted and applied to the separation/purification of biological products based on any number of physical, biological, and/or chemical characteristics. Thus, the intended purpose of Ladiwala is to enrich/purify a desired product from a mixture that further comprises undesired product/contaminants. It was acknowledged that Ladiwala does not teach a pooling step nor does Ladiwala teach an elution step wherein contaminants remain bound to the chromatography material (Ladiwala teaches contaminants are removed in the flow-through from the overload binding step). However, it is noted Brown teaches overloading of ion-exchange membrane adsorbers as the final purification step in the production of mAbs (monoclonal antibodies) produced from CHO (Chinese-hamster ovary) cells wherein the preferential binding of impurities over antibody product was exploited such that impurities were retained on the membrane adsorbers while there was breakthrough of purified antibodies. Thus, Brown establishes that “overload” chromatography may also be performed such that a chromatography matrix may be selected such that the desired product flows through, while the contaminants remain preferentially bound to the column; such a mode of operation has the same intended result of enriching/purifying a desired product. It is further noted that binding capacity, partition coefficient, pH, and conductivity were recognized as antibody purification variables which achieve a recognized result and as set forth in MPEP 2144.05, as identified in the previous Office Action; thus, optimization of an elution buffer to preferentially/only elute mAbs versus impurities/contaminants would be considered routine optimization. Furthermore, Brown elucidated the binding properties of the mAbs and contaminant proteins as demonstrated in Figure 8, which reveals preferential elution of mAb at low salt concentration (i.e., between fractions 2 and 4) wherein milligrams of antibody could be eluted with only nanograms of CHOP co-eluting; Brown states that (i) because the gradient moves from low to high salt concentration, the position in the gradient elution provides some insight into the strength of binding wherein the results suggest that gentamicin binds stronger than CHOP, which binds stronger than monomers; and (ii) as mAb loading increased from 1 to 15 kg mAb/L membrane, the levels of monomer decreased, while CHOP and gentamicin increased possibly because CHOP and gentamicin displace monomers on the membrane surface (e.g., during overloading wherein more mAb would be expected to be in the flowthrough) (Page 68, Column 2, Paragraph 1). As such, it would be within the purview of one having ordinary skill in the art that under the mode of operation of Brown, in addition to antibody obtained during the overloading step, sufficiently purified antibody may also be obtained during the elution step and it would be desirable to pool as much sufficiently pure product as possible. While the Ladiwala reference teaches a method of enriching a biological product, comprising an “overload bind and elute” mode of operation; while the exact method presented by Ladiwala teaches preferentially binding the biological product of interest (e.g., mAb) to the chromatography material, Brown suggests that such a method can be modified to preferentially bind impurities/contaminants to the chromatography material. Thus, while Ladiwala teaches one embodiment of “overload bind and elute” mode, it is not considered to teach away from the instant invention as there are alternate disclosures in the prior art, i.e., Brown, that suggest other embodiments that Ladiwala does not does not criticize, discredit, or otherwise discourage. Additionally, the desired outcome of both Ladiwala and Brown are the same: enrich/purify mAb and remove/reduce impurities and contaminants. Thus, any modification of Ladiwala based on the teachings of Brown is not considered to render the method unsatisfactory for its intended purpose, but rather presents an alternate approach to achieve the same result.
With regard to argument (iv), Applicant is reminded that preferred embodiments are not the only teaching of a reference. “The use of patents as references is not limited to what the patentees describe as their own inventions or to the problems with which they are concerned. They are part of the literature of the art, relevant for all they contain.” In re Heck, 699 F.2d 1331, 1332-33, 216 USPQ 1038, 1039 (Fed. Cir. 1983) (quoting In re Lemelson, 397 F.2d 1006, 1009, 158 USPQ 275, 277 (CCPA 1968)).
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A reference may be relied upon for all that it would have reasonably suggested to one having ordinary skill the art, including nonpreferred embodiments. Merck & Co. v. Biocraft Laboratories, 874 F.2d 804, 10 USPQ2d 1843 (Fed. Cir.), cert. denied, 493 U.S. 975 (1989). See also > Upsher-Smith Labs. v. Pamlab, LLC, 412 F.3d 1319, 1323, 75 USPQ2d 1213, 1215 (Fed. Cir. 2005)(reference disclosing optional inclusion of a particular component teaches compositions that both do and do not contain that component); < Celeritas Technologies Ltd. v. Rockwell International Corp., 150 F.3d 1354, 1361, 47 USPQ2d 1516, 1522-23 (Fed. Cir. 1998) (The court held that the prior art anticipated the claims even though it taught away from the claimed invention. “The fact that a modem with a single carrier data signal is shown to be less than optimal does not vitiate the fact that it is disclosed.”). Disclosed examples and preferred embodiments do not constitute a teaching away from a broader disclosure or nonpreferred embodiments. In re Susi, 440 F.2d 442, 169 USPQ 423 (CCPA 1971). “A known or obvious composition does not become patentable simply because it has been described as somewhat inferior to some other product for the same use.” In re Gurley, 27 F.3d 551, 554, 31 USPQ2d 1130, 1132 (Fed. Cir. 1994). Furthermore, “[t]he prior art’s mere disclosure of more than one alternative does not constitute a teaching away from any of these alternatives because such disclosure does not criticize, discredit, or otherwise discourage the solution claimed….” In re Fulton, 391 F.3d 1195, 1201, 73 USPQ2d 1141, 1146 (Fed. Cir. 2004). The exemplary embodiment argued regarding sialylated antibodies is not pertinent to the instant claims, which are drawn to a generic method of antibody purification. Ladiwala specifically indicates that methods of the invention can be adapted and applied to the separation/purification of biological products based on any number of physical, biological, and/or chemical characteristics (Paragraph 0038). The method of Ladiwala may therefore be applied in a variety of applications wherein the property/properties utilized for separation/purification may be any given property unique to the desired product compared to undesired products/contaminants. Brown discloses an alternative mode of operation to Ladiwala that exploits binding properties of antibodies versus contaminants. Thus, modification of the methods of Ladiwala and/or Brown to exploit different properties for purification of a given desired product from undesired products/contaminants is within the purview of one having ordinary skill in the art.
With regard to argument (v), obviousness does not require absolute predictability, only a reasonable expectation of success, i.e., a reasonable expectation of obtaining similar properties. See, e.g., In re O’Farrell, 853 F.2d 894, 903, 7 USPQ2d 1673, 1681 (Fed. Cir. 1988). Both Ladiwala and Brown disclose the use of overload and elute methods for the purification/enrichment of biological products (e.g., antibodies) wherein undesired products/contaminants can be selectively removed utilizing column chromatography, and thus the combination of teachings would be reasonably expected to yield a method of purifying an antibody with a reasonable expectation of success as established by both Ladiwala and Brown; the selected mode of operation does not change the outcome of obtaining enriched/purified product and as such there is reasonable expectation of success in combining the teachings of Brown and Ladiwala in view of the teachings of Voitl.
With regard to argument (vi), the additional of a pooling step as suggested by Brown to the method of Ladiwala does not add “extra work for no apparent reason”. Modifying the method of Ladiwala to operate in the alternative mode of Brown yields a method of enrichment/purification in which antibody elutes from the column during the overload step (impurities remain bound). Brown further suggests selective elution of antibody that may have bound the column, wherein the secondary elution step allows for additional elution/collection of antibody product. Pooling the antibody eluted during the overload step with the antibody specifically eluted from the column during a second elution step would increase the total amount of purified antibody collected; as such the “extra work” of adding a pooling step serves the purpose of improving/optimizing the purification method in which the maximum amount of purified product is obtained.
With regard to argument (vii), it is noted that “[a]ny judgement on obviousness is in a sense necessarily a reconstruction based on hindsight reasoning, but so long as it takes into account only knowledge which was within the level of ordinary skill in the art at the time the claimed invention was made and does not include knowledge gleaned only from applicant’s disclosure, such a reconstruction is proper.” In re McLaughlin 443 F.2d 1392, 1395, 170 USPQ 209, 212 (CCPA 1971). Ladiwala indicates that an advantage of utilizing the “overload bind and elute” mode of operation is that the biological product mixture obtained has been enriched with a higher concentration of product having the selected (target) characteristic compared to the product mixture prior to application of the overload bind and elute purification step (Paragraph 0037). Furthermore, Brown discloses that overload chromatography is an effective application of a purification technology that is uniquely advantageous to membranes, as it lends itself to the large volume pools typically encountered downstream of Protein A, wherein overall the results of the study show that this approach can be used as a rapid, high-yielding, final purification step for the production of mAbs (Page 69, Column 2, Paragraph 2). Thus, modification of Ladiwala based on the teachings of Brown, and Voitl, would still be expected to result in high yield and high purity mAbs, wherein high-volume processing is also a viable option; as such the results/features observed in instant Examples 5-10 are not considered “unexpected”. Particularly, the combination of teachings from Ladiwala and Brown, particularly as pertains to the pooling step instantly claimed, would be expected to yield and improved purification method because the amount of product recovered that is purified would be increased; residual antibody that may have bound the chromatography matrix can be specifically collected at a high degree of purity during an elution step and it would be within the purview of one having ordinary skill in the art to combine the product from said elution step with the purified product of the overload step in order to increase the overall yield of purified product (which is the intended purpose of the methods of both Ladiwala and Brown).
As such, the claim rejections under 35 U.S.C. 103, as updated above for clarity, are deemed proper and are maintained.
Conclusion
Claims 1, 5-6, 8-9, 11-16, 21-22, and 31-38 are pending. Claims 8-9 and 12 are withdrawn. Claims 1, 5-6, 11, 13-16, 21-22, and 31-38 are rejected. No claims are allowed.
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/ALYSSA RAE STONEBRAKER/Examiner, Art Unit 1642
/SAMIRA J JEAN-LOUIS/Supervisory Patent Examiner, Art Unit 1642